Creatine, a popular nutritional
supplement renowned for enhancing athletic performance and muscle strength, does
not improve exercise outcomes in patients with chronic obstructive pulmonary
disease (COPD), according to a new study. The randomized, placebo-controlled,
double-blind study provided the most powerful evidence to date that the effect
of creatine (Cr) supplementation was negligible at best among these
patients.
“We have evidence to suggest Cr
uptake into muscles [in COPD patients] but are unable to explain why an increase
in muscle Cr did not enhance training,” wrote the study’s lead author, Sarah
Deacon, M.D., specialist registrar at the Institute for Lung Health at Glenfield
Hospital in Leicester, England.
The results were published in the
first issue for August of the American Journal of Respiratory and Critical
Care Medicine by the American Thoracic Society
(ATS).
Cr supplementation has been shown
to improve short-burst, high-intensity exercise function in athletes, as well as
enhancing isometric muscle strength, lower body endurance and lean body mass in
the elderly. To determine whether Cr supplementation could similarly enhance the
physical condition of COPD patients, Dr. Deacon and co-researchers recruited 100
patients with COPD to either receive Cr or a placebo over the course of a seven
week pulmonary rehabilitation program.
Those who were randomized to the
placebo group were give lactose supplements that appeared identical to the
Cr-containing supplements. Following a five-day loading period (22g/d Cr or 24
g/d lactose) each subject followed maintenance dosing of 3.76 or 4 g of Cr or
lactose respectively.
Of the original 100 subjects, 80
successfully completed the study. In both control and Cr groups, there were
statistically significant improvements in functional and muscular performance
during the loading phase, but no differences were seen between the groups. The
Cr group also showed a greater, but non-significant percentage of improvement in
the incremental shuttle walking test with loading and after pulmonary
rehabilitation, but additional analysis still showed no overall effect between
it and the placebo group.
“The most likely explanation is
that any benefits of creatine have been submerged by the large training effect
of physical training alone,” wrote Dr. Deacon.
This study, therefore, further validates that
there is no substitute for the old-fashioned hard work that is an essential
element of pulmonary rehabilitation. “Those of us interested in pulmonary
rehabilitation are happy to see confirmation of the beneficial effects of
exercise training…. This information indicates that creatine supplementation not
be viewed as a good substitute for exercise training—good news for adepts of
pulmonary rehabilitation,” wrote Francoise Maltais, M.D., Didier Saey, Ph.D.,
and Richard Debigare, Ph.D., all of the Centre de Recherche de l’Hospital Laval
Quebec in Canada.
“Without minimizing the
importance of the quest to optimize the results of pulmonary rehabilitation, we
had to appreciate that only a small portion of patients with COPD actually
engage in pulmonary rehabilitation….so improved [access] is important for PR to
achieve its full potential from a public health
perspective.”
Dr.
John Heffner, past president of the ATS, commented that “these and other studies
are finally gaining recognition that pulmonary rehabilitation is an essential
element of comprehensive care for patients with COPD. The weight of the evidence
has succeeded in gaining Medicare payment for rehabilitation services, which has
been one of our major hurdles to access.”
Source: American Thoracic Society. August 2008.